Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=false, destructiveHint=true, and idempotentHint=false, so the safety profile is covered. The description adds real value by disclosing the return value (DNS verification token), but it does not explain why the operation is destructive — e.g. whether an existing custom domain is replaced or dropped — which is exactly the context the destructiveHint raises.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two short sentences, front-loaded with the action and followed by the return value; nothing is wasted. The terseness borders on under-specification rather than verbosity.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a destructive, non-idempotent mutation with two undocumented parameters and no output schema, the description should explain the identifier, the domain format, and the verification follow-up. It only covers the return token, leaving the calling agent to guess the rest.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, so the description must carry the burden and does not. It never says whether "id" is the deployment/app identifier or what "domain" should look like (bare hostname vs URL), despite the schema's 253-char constraint hinting at a full hostname.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

"Attach a custom domain" gives a specific verb and resource, and the second sentence states what comes back. It is clear on its own, but it never distinguishes itself from the adjacent deployments_removeCustomDomain and deployments_verifyCustomDomain, which an agent must choose between in the same workflow.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

There is no when-to-use guidance, no statement of prerequisites (domain ownership, DNS state), and no pointer to deployments_verifyCustomDomain for the follow-up step. The agent is left to infer the attach-then-verify sequence entirely from sibling names.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.